Question: Is ${221166}$ divisible by $4$ ?
Answer: A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{2211} {66} = \gray{2211} \gray{00} + {66} $ Because $221100$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${66}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $66$ , divisible by $4$ No, $66$ is not divisible by $4$, so $221166$ is also not divisible by $4$.